Role of oxygen vacancies in Co/Ni Substituted CeO2: A comparative study

Abstract

Single phase Co/Ni substituted CeO2 nanoparticles reveal the importance of oxygen vacancies on the electronic properties of the materials. The effect of Co/Ni substitution on the structural, optical, and photoluminescence properties of CeO2 have been studied systematically. Lattice shrinks and hence strain increase owing to incorporation of Co/Ni in CeO2. Optical absorption analysis shows a red shift in band-gap with Co/Ni substitution. Photoluminescence studies reveals increase in defect concentration which causes quenching of PL emission. Vibration modes at ~460 cm−1 in Raman spectra indicates incorporation of Co/Ni in CeO2 lattice whereas a broad peak appearing at ~ 540–640 cm−1 with substitution depicts the defects related to the increase in oxygen vacancy. X-ray absorption (XAS) studies show that Co/Ni substitution maintains local structure while Ce4+ → Ce3+ concentration increases to preserve the charge neutrality in lattice. © 2018 Elsevier Ltd and Techna Group S.r.l.